Increasing communications bandwidth is desirable because it facilitates more rapid transfer of information. In one technique for increasing bandwidth, referred to as “polarization reuse,” two separate information streams are transmitted as two orthogonal signals, using two orthogonally oriented antennas. The signals are received by two orthogonally oriented antennas, each of which receives one of the two orthogonal signals and is coupled to a receiver that interprets the signal received by that antenna to obtain the corresponding information stream. Such an arrangement enables twice as much information to be transmitted as would be possible with an antenna having only a single polarization. In principle, ideal polarization orthogonality provides perfect isolation between the two independent signal components; in practice, only nominal orthogonality is achieved, and a means to achieve sufficient isolation is required to avoid signal reception degradation.
However, to successfully interpret both of the information streams generated during polarization reuse, past approaches have stringently controlled cross-coupling between the two orthogonal signals by passive and/or adaptive design techniques. For example, if one of the receiving antennas receives contributions from both of the signals, then it may become difficult for the corresponding receiver to interpret the signal to obtain the corresponding information stream. Much effort has been put forth to avoid cross-coupling between orthogonal signals. For example, passive antenna design techniques may be used to enhance the polarization purity of each of the two signals. Or, for example, active design techniques may be used to dynamically maintain signal isolation through adaptive cross polarization cancellation networks.